Shift to a Younger Age and Regional Differences in Inflammatory Bowel Disease in Korea: Using Healthcare Administrative Data

© 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.Background: Research using healthcare administrative data with a validated algorithm can reveal the real-world data of rare diseases. Aims: We investigated an accurate algorithm for detecting incident cases of inflammatory bowel disease (IBD) from healthcare data and analyzed the nationwide population-based epidemiological features in Korea. Methods: Healthcare data from Songpa-Kangdong districts in Seoul were extracted from the National Health Insurance Service and analyzed to identify the best algorithm reflecting the cohort data. The most accurate criterion was applied to the entire database for further analysis. Results: With the selected working criteria, 37,555 incident cases of IBD (Crohn’s Disease [CD], 13,130; ulcerative colitis [UC], 24,425) were identified from 2005 to 2016. The male-to-female ratio was 2.5:1 for CD and 1.4:1 for UC. Over 12 years, the annual standardized incidence rate (SIR) per 100,000 people increased from 1.6 to 2.7 and 3.8 to 4.3 for CD and UC, respectively. The peak age at diagnosis of UC shifted from 55–59 years to 20–24 years, whereas that of CD shifted from 19 to 17 years. The SIR of CD was higher in metropolitan areas than in non-metropolitan areas. Conclusions: This nationwide population-based epidemiologic study of Korean IBD revealed a gradual increase in the incidence rates and a notable shift toward younger age at diagnosis. Males were predominant in both CD and UC. There was an urban–rural difference in the SIR of CD.N